We have invented a new dermal exciser or skin cutter instrument. The present invention is directed in particular to a medical instrument for excising an ellipsoid or football-shaped sample of a patients' skin.
It is very important to have an early and thorough dermatological examination of any suspected abnormality or growth on the skin. Early diagnosis, detection and then appropriate treatment can insure a full and speedy patient recovery, obviating the need for surgery or other invasive therapeutic techniques.
Dermatological examination of a patient can indicate a need to remove a sample of the patient's skin for further evaluation. Thus, a physician's examination of a patient's skin may reveal a variety of warts, moles, lesions, protuberances, calcifications, dry patches, tumors, and discolorations, all of which can be referred to as "growths", and for which laboratory study is deemed prudent. Sometimes such study shows nothing amiss. Sometimes the study indicates a need for further examination of the patient. Occasionally, examination of an excised growth indicates that the patient has melanoma, or any of a number of other disorders with may be life-threatening.
Preferably, the skin sample excised includes the entire skin growth of interest as well as a small area of the normal appearing skin around the growth, for comparative analysis. Laboratory tests can assess any influence on the normal skin by the growth. The amount of invasion or disruption of normal skin function by the growth can be used as a measure of the progress of a disease state.
It is highly preferred that when a sample of a patient's skin is removed for examination, that the skin sample have an ellipsoid or football shape. Removing a skin sample with such a shape has numerous advantages, including rapid healing of the lesion left by the excision, and formation of a regular, linear scar. Thus, when the ellipsoid-shaped skin sample of skin is removed so that the long axis of the ellipsoid-shaped skin sample is parallel to the orientation of the elastic fibers at the location on the skin from which the skin sample is removed, then a cosmetically desirable regular, linear scar will form as the lesion heals. Such a scar shape forms because the elastic fibers "close ranks" around the lesion. A further advantage of excising an ellipsoid-shaped skin sample, is that such a sample shape usually provides, in addition to the growth, sufficient normal skin for a comparative examination.
Frequently, the desired ellipsoid-shaped skin sample is removed from the patient by a physician using a scalpel. Such direct physician involvement in the actual skin sample excision is not desired because it requires direct physician involvement in a minor procedure. A busy dermatological practice can require a large number of skin sample excisions daily, particularly in sunny locations with a large number of light-skinned people, such as Southern California. The physician is thereby prevented from addressing the needs of other patients who may have more acute conditions.
Additionally, nonphysician staff are prohibited by most states from using a scalpel to excise skin samples. Nurses and medical assistants are though allowed to use, under physician supervision, nonscalpel methods for removal of skin samples. There is a known nonscalpel tool that can be used for excising skin samples. This is the dermal punch tool,
The dermal punch tool can be used by a trained nonphysician to remove a skin sample. The punch tool is operated by placing it on the site of the patient's skin at which an excision is desired, and then pressing down quickly on the tool, resulting in the punching-out of a skin sample.
The dermal punch tool has several disadvantages and shortcomings. First, it permits removal of only a conical or cylindrical-shaped sample of skin. Skin samples so shaped tend to be difficult to section, stain and to examine microscopically. Second, use of the dermal punch tool leaves a circular skin lesion that can require suturing. Even when the skin lesion left by the dermal punch tool is small enough to heal without a need for stitches, the healed skin will typically have an unattractive irregularly-shaped scar. Additionally, the healed skin has an unsightly puckered appearance.
Third, the skin sample is difficult to remove from the cavity of the punch part of the punch tool after skin excision, because it tightly occupies the cavity of the punch. Usually, the skin sample must be pried loose with a needle or other pointed object or the punch tool is shaken vigorously to loosen the skin sample. The skin sample can thereby be damaged, or lost.
A damaged skin sample can give anomalous, or "false positive" test results. Furthermore, loss of the skin sample can be a very serious matter, because the excision cannot be repeated--the growth of interest having already been removed. More invasive procedures, such as surgery, may then be required to assist diagnosis of a potential disease state in the patient.
Fourth, the dermal punch tool permits removal of only a circular piece of skin. Sometimes, the growth on the patient's skin is not circularly-shaped. Thus, the punch tool can result in removal of only a part of the growth and of too little of the surrounding skin for an effective comparative analysis. Cutting into the possibly abnormal growth and leaving part of it behind on the patient's skin can have serious consequences. A precancerous growth can be motivated by the injury to become cancerous. Alternately, an already cancerous tissue can, due to the injury, metastasize, when cancer cells dislodged by the incomplete excision disseminate to other parts of the body.
Additionally, because the elastic fibers of the skin do not run in circular patterns, removal of a circular skin sample almost inevitably results in some distortion of the skin layers within the skin sample. This occurs even if the skin sample is easily removed from the cavity of the punch part of the dermal punch tool without damaging the skin sample. Such skin sample distortion can again make analysis and diagnosis difficult if not impossible.
Fifth, the nature of the cutting surface of the dermal punch tool causes it to become too blunt for further use after the excision of only a few skin samples.
Thus, there is a real need for a skin cutter instrument that: (1) removes an ellipsoid-shaped sample of a patient's skin; (2) facilitates a thorough and accurate laboratory examination of the excised skin sample; (3) leaves a skin lesion that can heal to a regular scar, without the need for suturing; (4) allows easy removal of an undamaged and undistorted excised skin sample from the instrument; (5) permits removal of an entire skin growth, thereby reducing the risk of a precancerous growth becoming cancerous, and of a cancerous growth metastasizing, and (6) remains sharp after multiple skin excisions.